UV Nitride Light Emitter Quantum Well Structure for Low-Voltage Efficiency
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Solution Overview
Problem
Nitride semiconductor light emitting elements that emit ultraviolet light have lower light emission efficiency compared to those emitting visible light, necessitating an improvement in their design to enhance ultraviolet light emission.
Innovation Solution
A nitride semiconductor light emitting element structure comprising an n-side semiconductor layer, a p-side semiconductor layer, an active layer with specific Al composition and thickness gradients, and an electron blocking layer, where the active layer includes a first and second well layer with varying Al composition ratios and thicknesses, and the electron blocking layer is formed in contact with the second well layer before the p-side semiconductor layer, optimizing the light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional active layer structure is used in nitride semiconductor light emitting elements, then the device can be manufactured with standard processes, but the light emission efficiency for ultraviolet light remains low
Solution Approach 1:
The active layer is divided into multiple quantum well layers (first quantum well layer, second quantum well layer, third quantum well layer) separated by barrier layers. Each quantum well layer has specific thickness and Al composition ratios that are optimized independently to enhance ultraviolet light emission efficiency while managing device complexity through modular design
Solution Approach 2:
Different regions of the active layer are assigned different Al composition ratios and thicknesses. The first quantum well layer has Al composition ratio x1, the second has x2, and the third has x3, where these ratios vary locally to optimize carrier confinement and light emission at different depths, improving overall ultraviolet emission efficiency
2Loss of energy
If the Al composition ratio is increased to improve ultraviolet light emission, then the light emission efficiency improves, but the forward voltage increases
Solution Approach 1:
The Al composition ratio is varied across different quantum well layers rather than using a uniform composition. The first quantum well layer uses Al composition ratio x1, the second uses x2, and the third uses x3, with specific relationships between these parameters optimized to balance light emission efficiency and forward voltage characteristics
Solution Approach 2:
The active layer structure employs dynamic variation in Al composition ratios and layer thicknesses to optimize performance. The gradient in composition ratios across the quantum well layers creates optimal conditions for carrier injection and recombination, improving light emission efficiency while controlling forward voltage through compositional grading
3Ease of manufacture
If a simpler active layer structure is used, then the manufacturing process is easier, but the ultraviolet light emission efficiency remains insufficient
Solution Approach 1:
The active layer is segmented into three distinct quantum well layers with barrier layers, allowing each layer to be optimized for specific functions. This segmentation enables improved ultraviolet light emission efficiency while maintaining a systematic manufacturing approach that builds upon standard epitaxial growth processes
Solution Approach 2:
The active layer employs a composite structure combining multiple quantum well layers with different Al composition ratios and thicknesses. This composite design integrates the advantages of different material compositions to achieve high ultraviolet emission efficiency while using conventional nitride semiconductor manufacturing techniques
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The described structure achieves high light emission efficiency and low forward voltage for ultraviolet light emission, addressing the inefficiencies in existing nitride semiconductor light emitting elements.
Implementation Method 1
a first well layer containing Al and emitting ultraviolet light, a second barrier layer containing Al, and a second well layer disposed in contact with the electron blocking layer, containing Al, and emitting ultraviolet light
Data Source
AI summary
A nitride semiconductor light emitting element includes: an n-side semiconductor layer; a p-side semiconductor layer; an active layer positioned between the n-side semiconductor layer and the p-side semiconductor layer; and an electron blocking layer positioned between the p-side semiconductor layer and the active layer. The active layer includes, successively from the n-side semiconductor layer side: a first barrier layer containing Al, a first well layer that contains Al and emits ultraviolet light, a second barrier layer containing Al, and a second well layer that is in contact with the electron blocking layer, contains Al, and emits ultraviolet light. An Al composition ratio of the second well layer is higher than an Al composition ratio of the first well layer. A thickness of the second well layer is less than a thickness of the first well layer.